Methods of processing semiconductor substrates, electrostatic carriers for retaining substrates for processing, and assemblies comprising electrostatic carriers having substrates electrostatically bonded thereto

ABSTRACT

A method of processing a substrate includes physically contacting an exposed conductive electrode of an electrostatic carrier with a conductor to electrostatically bond a substrate to the electrostatic carrier. The conductor is removed from physically contacting the exposed conductive electrode. Dielectric material is applied over the conductive electrode. The substrate is treated while it is electrostatically bonded to the electrostatic carrier. In one embodiment, a conductor is forced through dielectric material that is received over a conductive electrode of an electrostatic carrier to physically contact the conductor with the conductive electrode to electrostatically bond a substrate to the electrostatic carrier. After removing the conductor from the dielectric material, the substrate is treated while it is electrostatically bonded to the electrostatic carrier. Electrostatic carriers for retaining substrates for processing, and such assemblies, are also disclosed.

RELATED PETENT DATA

This patent resulted from a continuation application of U.S. patentapplication Ser. No. 13/169,915, filed Jun. 27, 2011, entitled “Methodsof Processing Semiconductor Substrates, Electrostatic Carriers forRetaining Substrates for Processing, and Assemblies ComprisingElectrostatic Carriers Having Subsrates Electrostatically BondedTherto”, naming Dewali Ray, Warren M Farnworth, And Kyle K Kirby asinventors, which is a divisional application of U.S. patent applicationSer. No. 11/780,628, filed Jul. 20,2007, now U.S. Pat. No. 7,989,022,entitled “Methods of Processing Semiconductor Substrates, ElectrostaticCarriers for Retaining Substrates for Processing, and AssembliesComprising electrostatic Carriers Having Substrates ElectrostaticallyBonded Thereto”, naming Dewali Ray, Warren M Farnworth, and Kyle K Kirbyas inventors, the disclosures of which are incorporated by refrence.

TECHNICAL FIELD

Embodiments disclosed herein pertain to methods of processingsubstrates, to electrostatic carriers for retaining substrates, and toassemblies comprising electrostatic carriers having substrateselectrostatically bonded thereto.

BACKGROUND

A plurality of integrated circuits is typically fabricated relative to asemiconductor wafer or other semiconductor substrate. The substrate issubjected to various treating steps, such as material growth,deposition, etching, ion implantation, etc., in forming the integratedcircuitry. Accordingly, the semiconductor substrate is subjected to aplurality of different treatments prior to completion. Recently, thesemiconductor substrates being processed have become increasinglythinner and fragile leading to different techniques for supporting theindividual substrates through the various different treatments to whichthey are subjected.

One manner of supporting such substrates is to adhere individualsubstrates to a rigid carrier with a temporary adhesive. At theconclusion of all processing, the semiconductor substrate is removedfrom the rigid carrier which can then be used again to process anothersemiconductor substrate. Use of such rigid carriers is not, however,without drawbacks. For example, considerable time is spent in preparingthe carrier for the adhesive bonding, the actual bonding process itself,and in the de-bonding which also includes cleaning processes withexpensive solvents. Further, the temporary adhesives can have poor hightemperature stability, and tend to outgas material which can adverselyeffect the treating of the semiconductor substrate.

Another manner of retaining semiconductor substrates for processing useselectrostatic carriers. Such enable reversible bonding of semiconductorsubstrates by electrostatic attraction forces which are induced by anear-permanent polarization state of one or more dielectric layers. Withelectrostatic carriers, a semiconductor substrate is received against adielectric side of a carrier substrate. The semiconductor substrate istypically provided at a ground potential, and suitable positive voltageis applied to a conductive electrode on the electrostatic carrier toprovide a positive/negative electrostatic attraction force at aninterface of the semiconductor substrate and electrostatic carrier. Theattraction force remains after removal of the external voltage sources,thereby enabling the semiconductor substrate to be treated with variousdifferent processing steps. At the conclusion of the various treatments,the electrostatic attraction force can be removed by shorting theelectrostatic carrier electrode and semiconductor substrate relative toone another, or by applying a suitable negative voltage to theelectrostatic carrier electrode.

Accordingly, the time for bonding and de-bonding is very short incomparison to use of temporary adhesives. Further, electrostatic bondingenables subsequent processing of the semiconductor substrates at veryhigh temperatures without the effects of outgassing, blistering, etc.Further, cleaning of the semiconductor substrate upon de-bonding that isrequired after de-bond using temporary adhesive technology can beeliminated.

However, commercially available electrostatic carriers are notpractically capable of wet immersion processing, for exampleelectroplating, wet etching, and wafer cleaning where the carrier withsubstrate bonded thereto is typically immersed in an aqueous liquid.This is because an electric path can be created within the liquid fromthe electrostatic carrier substrate electrode to the semiconductorsubstrate, thereby removing the electrostatic attraction force andde-bonding the semiconductor substrate from the electrostatic carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of a substrate and electrostaticcarrier in proximity relative to one another.

FIG. 2 is a diagrammatic sectional view of the substrate and theelectrostatic carrier of FIG. 1 in contact with one another.

FIG. 3 is a view of the FIG. 2 assembly at a step subsequent to thatdepicted by FIG. 2.

FIG. 4 is a view of the FIG. 3 assembly at a step subsequent to thatdepicted by FIG. 3.

FIG. 5 is a view of the FIG. 4 assembly at a step subsequent to thatdepicted by FIG. 4.

FIG. 6 is a view of the FIG. 5 assembly at a step subsequent to thatdepicted by FIG. 5.

FIG. 7 is a view of the substrate and electrostatic carrier of FIG. 6 inproximity relative to one another at a step subsequent to that depictedby FIG. 6.

FIG. 8 is a diagrammatic sectional view of a substrate and anelectrostatic carrier in contact with one another.

FIG. 9 is a view of the FIG. 8 assembly at a step subsequent to thatdepicted by FIG. 9.

FIG. 10 is a view of the FIG. 9 assembly at a step subsequent to thatdepicted by FIG. 9.

FIG. 11 is a view of the FIG. 9 assembly at an alternate possible stepsubsequent to that depicted by FIG. 9.

FIG. 12 is a view of the FIG. 9 assembly at another alternate possiblestep subsequent to that depicted by FIG. 9.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Embodiments of the invention include methods of processing substrates,electrostatic carriers for retaining a substrate for processingindependent of method, and assemblies including electrostatic carriersand substrates electrostatically bonded thereto independent of method.

Certain embodiments of methods of processing a substrate are initiallydescribed with reference to FIGS. 1-7. Referring initially to FIGS. 1and 2, a substrate to be processed is indicated generally with referencenumeral 10 and an electrostatic carrier is indicated generally withreference numeral 20. In one embodiment, substrate 10 comprises asemiconductor substrate. In the context of this document, the term“semiconductor substrate” or “semiconductive substrate” is defined tomean any construction comprising semiconductive material, including, butnot limited to, bulk semiconductive materials such as a semiconductivewafer (either alone or in assemblies comprising other materialsthereon), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductive substrates described above. Electrostatic carrier 20 isdepicted as diagrammatically comprising some suitable carrier substrate21 having an exposed conductive electrode 22. Additional electrodes andcircuitry might be associated with electrostatic carrier 20 for creatingan electrostatic charge as will be appreciated by the artisan. Furtherand accordingly, aspects disclosed herein apply to existing andyet-to-be developed electrostatic carriers and substrates. FIG. 1depicts substrate 10 and electrostatic carrier 20 separate and inproximity relative one another, whereas FIG. 2 discloses such in anexample contacting relationship at or forming an interface 15 inpreparation for suitable electrostatic interconnection/bonding.

Referring to FIG. 3, exposed conductive electrode 22 of electrostaticcarrier 20 has been physically contacted with a conductor 25 toelectrostatically bond substrate 10 to electrostatic carrier 20.Multiple conductors 25 (not shown) might be used with multipleconductive electrodes (not shown) on electrostatic carrier 20, or only asingle conductor 25 might be used in connection with a single conductiveelectrode of electrostatic carrier 20 (as shown). Regardless and by wayof example only, the embodiment of FIG. 3 depicts application of asuitable positive voltage from conductor 25 to electrostatic carrier 20through exposed conductor 22 while the back-side of substrate 10 isprovided at a ground potential 27. Thus, a suitable positive/negativeelectrostatic attraction force is provided at interface 15 of substrate10 with electrostatic carrier 20.

Substrate 10 may be treated prior to electrostatic bonding withelectrostatic carrier 20 either for some fabrication aspect associatedwith forming integrated circuitry and/or to facilitate electrostaticbonding. For example and by way of example only, substrate 10 might besubjected to suitable treating to dry it for electrostatic bonding, forexample including a bake at elevated temperature or cleaning with asuitable desiccant or solvent.

Referring to FIG. 4, conductor 25 (not shown) has been removed fromphysically contacting exposed conductive electrode 22. Further,dielectric material 30 has subsequently been applied over conductiveelectrode 22. In one embodiment, dielectric material completely coversconductive electrode 22 (as shown). In one embodiment, dielectricmaterial 30 is at least 0.1 micron thick and in another embodiment atleast 0.5 micron thick, although lower thicknesses might also be used.In one embodiment, an upper thickness is 700 microns, although greaterthicknesses might also be used. Dielectric material 30 might compriseone or more different dielectric materials, and regardless might behomogenous, non-homogenous, and/or comprise multiple different layers orregions not all of which are necessarily dielectric. Regardless,dielectric material 30 ideally provides an effective electricallyinsulating shield over conductive electrode 22 relative to anynon-penetrating material that comes into contact with the outer surfaceof dielectric material 30. Dielectric material 30 may cover an entiretyof the back-side of electrostatic carrier 20, or may only cover aportion thereof while being received over conductive electrode 22.

In one embodiment, dielectric material 30 comprises, consistsessentially of, or consists of a polymer. In one embodiment, dielectricmaterial 30 comprises, consists essentially of, or consists of one ormore of photoresist and polyimide. Dielectric material 30 may bedeposited by any existing or yet-to-be developed technique, includingphysical vapor deposition, chemical vapor deposition, atomic layerdeposition, liquid spin coating, lamination processes, etc. In oneembodiment, dielectric material 30 comprises, consists essentially of,or consists of adhesive tape which has been adhered to conductiveelectrode 22. By way of example only, one example reduction-to-practiceadhesive tape is Kapton™ polyimide available from DuPont ElectronicTechnologies of Circleville, Ohio. An example reduction-to-practicephotoresist is SPR 220-4.5 available from Rohm & Haas Chemicals,Philadelphia, Pa. Other tapes and/or photoresist and/or polymers and/orother dielectric materials are of course contemplated, includingadditional material described below. Ideally, dielectric material 30 ischemically and otherwise resistant to treating activity to whichelectrostatically bonded substrate 10 will be subsequently exposed.

In one embodiment, dielectric material 30 is effective to coverconductive electrode 22 sufficiently to preclude electrical shorting ofthe upper/outer surface of depicted substrate 10 with conductiveelectrode 22 regardless of the atmosphere or environment within whichthe electrostatically bonded substrate 10 is exposed.

Referring to FIG. 5, semiconductor substrate 10 while electrostaticallybonded with electrostatic carrier 20 is treated in one or more manners,which is diagrammatically indicated by way of example only by downwardlydirected arrows 35. Any existing or yet-to-be developed treating is ofcourse contemplated. By way of example only, such might be any of wetprocessing, dry processing, etching, ion implantation, polishing,grinding, evaporation, annealing, lithography, etc. In but oneembodiment, the treating comprises applying a liquid to substrate 10,and in accordance with an aspect which motivated the inventionelectrostatic carrier 20 with electrostatically bonded substrate 10 isimmersed into liquid, for example into a liquid bath for etching,electroplating, cleaning, etc. Of course, substrate 10 aselectrostatically bonded to electrostatic carrier 20 might be subjectedto a plurality of the same or different treating steps.

In one embodiment, dielectric material 30 is at some point removed fromover conductive electrode 22 after an act of treating substrate 10, forexample as shown in FIG. 6. Removal of dielectric material 30 (notshown) might occur by any suitable process, for example peeling tapeaway from conductive electrode 22, solvent dissolving of dielectricmaterial 30, wet etching, dry etching, polishing, grinding, etc.

In one embodiment, after removing dielectric material 30 conductiveelectrode 22 is physically contacted with a suitable conductor toincrease electrostatic charge to the electrostatically bonded substrate10. Such might be conducted, by way of example only, where theelectrostatic charge had decreased over time and additional attractiveelectrostatic charging force was desired, for example for continuedtreating of substrate 10 as electrostatically bonded to electrostaticcarrier 20. By way of example only, such subsequent treating might occurwith or without re-covering of conductive electrode 22 with the same orother dielectric material.

Alternately or in addition thereto, and by way of example only, afterremoving dielectric material 30, conductive electrode 22 can bephysically contacted with a conductor effective to de-bond substrate 10from electrostatic carrier 20, for example as shown in FIG. 7. By way ofexample only, application of a suitable negative voltage to conductiveelectrode 22 by a conductor 25 can reduce or eliminate the electrostaticattraction force sufficiently to enable easy separation of substrate 10from electrostatic carrier 20. Alternately and by way of example only inbut one embodiment, conductor 25 for de-bonding might be forced throughdielectric material 30, with the dielectric material 30 thereafterperhaps remaining or being removed from electrostatic carrier 20.

Example additional embodiment methods of processing a substrate are nextdescribed with reference to FIGS. 8-12. Like numerals from the firstdescribed embodiments are utilized where appropriate, with differencesbeing indicated with small-letter suffixes or with different numerals.FIG. 8 depicts substrate 10 received against electrostatic carrier 20prior to electrostatic bonding. A dielectric material 30 is providedover conductive electrode 22 prior to such electrostatic bonding. In oneembodiment, dielectric material is provided to completely coverconductive electrode 22. Dielectric material 30 in certain embodimentsmight comprise any of the above-described exemplary dielectric materials30. Yet in one embodiment, dielectric material 30 is a self-healingmaterial. A self-healing material is a term of art for a material whichhas an inherent built-in ability to at least partially repair mechanicaldamage occurring thereto. In one embodiment, an example self-healingdielectric material comprises a parylene. In one embodiment, anotherexample self-healing dielectric material comprises polyimide comprisingmicro-encapsulated healing agents, for example polycyclic organicmoieties or functionalized derivatives thereof with dicyclopentadieneresins being but one example. Self-healing dielectric materials mightalso be utilized in connection with the FIGS. 1-7 embodiments describedabove. Further in certain embodiments in connection with FIG. 8 andsubsequent processing, dielectric material 30 might not be self-healing.Also, dielectric material 30 might comprise a combination ofself-healing material and material that is not self-healing.

Referring to FIG. 9, a conductor 25 has been forced through dielectricmaterial 30 to physically contact conductor 25 with conductive electrode22 to electrostatically bond substrate 10 to electrostatic carrier 20.Accordingly in one embodiment, such forcing of conductor 25 throughdielectric material 30 forms a hole 40 therethrough at least whileconductor 25 penetrates through dielectric material 30.

Conductor 25 is removed from dielectric material 30. FIG. 10 depicts oneexample embodiment wherein dielectric material 30 closes hole 40 (notshown) upon removing of conductor 25 from dielectric material 30, forexample as ideally occurs with a self-healing dielectric material. Someevidence of hole 40 may or may not exist after removing conductor 25from a self-healing material 30. Further and regardless, hole closuremight also occur in the absence of use of a self-healing material, forexample as shown in FIG. 11. FIG. 11 depicts dielectric material 30 a ascomprising a suitable elastomeric material, for example rubber, whichmight close back in on itself after removal of conductor 25, forming acrack 42 which mechanically seals sufficiently tight in one embodimentto preclude passage of liquid or other material therethrough toconductive electrode 22.

Alternately, at least one embodiment of the invention contemplates thedielectric material not closing the hole upon removing of the conductor,for example as shown in FIG. 12 in connection with a dielectric material30 b. Such depicts hole 40 remaining after removal of conductor 25 (notshown). In such embodiment, remaining hole 40 may or may not precludepassage of material therethrough to conductive electrode 22 duringtreating of electrostatically bonded substrate 10, or otherwise. In oneexample, application of a dielectric material over conductive electrode22 may facilitate time of storage of sufficient electrostatic bondingcharge by reducing degree of charge dissipation through conductiveelectrode 22 (even, for example, if only being exposed to a non-treatingroom ambient) were it not covered to at least some degree by dielectricmaterial. Regardless, in one embodiment where the forcing of theconductor through dielectric material 30 b for the electrostaticcharging forms a hole which does not close upon removing of theconductor, the dielectric material is ideally effectively hydrophobic incombination with hole size to preclude contact of an aqueous liquidthrough the hole to the conductive electrode in spite of the hole notclosing. One example suitable hydrophobic dielectric material comprisespolytetrafluoroethylene.

Regardless, substrate 10 while electrostatically bonded to electrostaticcarrier 20, for example in any of the FIGS. 10-12 embodiments, istreated for example in any manner as described above in connection withthe FIG. 5 embodiments. In one particular embodiment, the treatingcomprises applying an aqueous liquid to substrate 10, including by wayof example only immersing electrostatic carrier 20 withelectrostatically bonded substrate 10 into one or more aqueous liquids.Regardless, at the conclusion of processing, a de-bonding voltagepotential might be applied by again forcing a conductor through thedielectric material 30 to contact conductive electrode 22 in any of theFIGS. 10-12 embodiments.

Further and by way of example only, embodiments of the inventionencompass methods of processing a substrate which comprise physicallycontacting a conductive electrode of an electrostatic carrier with aconductor to electrostatically bond a substrate to the electrostaticcarrier. The conductor is removed from physically contacting theconductive electrode, and dielectric material is provided over theconductive electrode. In one embodiment, the dielectric material isprovided to completely cover the conductive electrode. Regardless, thedielectric material might be provided over the conductive electrodebefore the physical contacting for electrostatic bonding (i.e., exampleembodiments described in connection with FIGS. 8-12) or the dielectricmaterial might be provided over the conductive electrode only after theact of physical contacting to provide the electrostatic bonding (i.e.,any of the embodiments described above in connection with FIGS. 1-7).

Embodiments of the invention also encompass electrostatic carriers forretaining a substrate for processing. For example in one suchembodiment, such comprises a carrier substrate having a conductiveelectrode adapted for physical contact with a conductor that applies avoltage effective to generate an electrostatic charge for retaining asubstrate to the carrier substrate for processing. The electrostaticcarrier in accordance with this example embodiment comprises aself-healing dielectric material which is received over the conductiveelectrode and through which the conductor is adapted to penetrate, forexample as described above in connection with the FIG. 8 embodimentelectrostatic carrier 20 independent of substrate 10. Yet, an embodimentof the invention also contemplates an assembly comprising the abovedescribed electrostatic carrier having a substrate 10 electrostaticallybonded thereto, also as shown by way of example only in FIG. 8.

In another embodiment, an electrostatic carrier for retaining asubstrate for processing comprises a carrier substrate having aconductive electrode adapted for physical contact with a conductor thatapplies a voltage effective to generate an electrostatic charge forretaining a substrate to the carrier substrate for processing. Adielectric adhesive tape is adhered to the conductive electrode, andindependent of whether a substrate is electrostatically bonded thereto.Nevertheless, an embodiment of the invention includes an assembly whichcomprises such an electrostatic carrier with dielectric adhesive tapeadhered to the conductive electrode having a substrate electrostaticallybonded to the electrostatic carrier. Regardless, in one embodiment, thedielectric adhesive tape completely covers the conductive electrode.

By way of example only in a further embodiment, an electrostatic carrierfor retaining a substrate for processing comprises a carrier substratehaving a conductive electrode adapted for physical contact with aconductor that applies a voltage effective to generate an electrostaticcharge for retaining a substrate to the carrier substrate forprocessing. At least one of photoresist and polyimide is received overthe conductive electrode, and independent of whether a substrate iselectrostatically bonded to the electrostatic carrier. Nevertheless, anembodiment of the invention encompasses an assembly comprising such anelectrostatic carrier having at least one of photoresist and polyimidereceived over the conductive electrode and having a substrateelectrostatically bonded to the electrostatic carrier. Regardless, inone embodiment, the at least one of polyimide and photoresist completelycovers the conductive electrode.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

We claim:
 1. An electrostatic carrier for retaining a substrate forprocessing, comprising: a carrier substrate; a conductive electrode onthe carrier substrate adapted for physical contact with a conductor thatapplies a voltage to generate an electrostatic charge for retaining asubstrate to the carrier substrate for processing; and a dielectricmaterial covering over the conductive electrode and through which theconductor is adapted to penetrate, the dielectric material comprisesmultiple different layers not all of which are dielectric.
 2. Theelectrostatic carrier of claim 1 wherein the dielectric materialcompletely covers the conductive electrode.
 3. The electrostatic carrierof claim 2 wherein the dielectric material completely covers a side ofthe substrate which comprises the conductive electrode.
 4. Theelectrostatic carrier of claim 1 wherein the dielectric materialcomprises a thickness of at least 0.1 micron.
 5. The electrostaticcarrier of claim 1 wherein the dielectric material comprises a thicknessof at least 0.5 micron.
 6. The electrostatic carrier of claim 1 whereinthe dielectric material comprises a thickness of no greater than 700microns.
 7. An electrostatic carrier for retaining a substrate forprocessing, comprising: a carrier substrate; a conductive electrode onthe carrier substrate adapted for physical contact with a conductor thatapplies a voltage to generate an electrostatic charge for retaining asubstrate to the carrier substrate for processing; and a dielectricmaterial covering over the conductive electrode and through which theconductor is adapted to penetrate, the dielectric material comprisesmultiple different regions not all of which are dielectric.
 8. Theelectrostatic carrier of claim 7 wherein the dielectric materialcompletely covers the conductive electrode.
 9. The electrostatic carrierof claim 8 wherein the dielectric material completely covers a side ofthe substrate which comprises the conductive electrode.
 10. Theelectrostatic carrier of claim 7 wherein the dielectric materialcomprises a thickness of at least 0.1 micron.
 11. The electrostaticcarrier of claim 7 wherein the dielectric material comprises a thicknessof at least 0.5 micron.
 12. The electrostatic carrier of claim 7 whereinthe dielectric material comprises a thickness of no greater than 700microns.
 13. An electrostatic carrier for retaining a substrate forprocessing, comprising: a carrier substrate; a conductive electrode onthe carrier substrate adapted for physical contact with a conductor thatapplies a voltage to generate an electrostatic charge for retaining asubstrate to the carrier substrate for processing; and a dielectricmaterial covering over the conductive electrode and through which theconductor is adapted to penetrate, the dielectric material beinghydrophobic and having a hole extending there-through which outwardlyexposes the conductive electrode.
 14. The carrier of claim 13 whereinthe dielectric material is effectively hydrophobic in combination withsize of the hole to preclude aqueous liquid from passing through thehole to contact the exposed conductive electrode.
 15. The electrostaticcarrier of claim 13 wherein the dielectric material comprises multipledifferent layers not all of which are dielectric.
 16. The electrostaticcarrier of claim 13 wherein the dielectric material comprises multipledifferent regions not all of which are dielectric.